Extruded plastic profiles for decorative and protective purposes such as side trims for automobiles, decorative trims for appliances and the like, have achieved considerable commercial success. These profiles could be bolted on or secured by clips or attached by contact cement or sealant compounds to various substrates. These methods of fastening are tedious, laborious and may damage the substrates to which the profiles are attached. Recently, foam tapes coated both sides with a pressure-sensitive adhesive such as "Macmount 9632" (trademark) or "Macmount 9760" (trademark) from Morgan Adhesives Company have been used in practice. Foam tapes as a means of fastening are extremely easy to apply and have many other advantages. Such foam tapes are highly conformable and fasten the profiles well to even curved or rough surfaces. They also absorb shock and do not damage the substrates.
Other ways of making laminates are also known. For instance, laminates of polyester foams to plastics can be made by means of adhesive or heat either in their finally cured state or by a polyester foam formed in situ in contact with a preformed plastic film. It is also taught in Canadian Pat. No. 564,307 issued Oct. 7, 1958, to Wilson et al, that polyesterdiisocyanate foams can be united before the film is completely cured, that is by combining a foamed product to an incompletely cured polyvinyl chloride in the form of a plastisol or organol. It is also taught in Canadian Pat. No. 828,134 issued Nov. 25, 1969, to Laberinti et al to weld foam polyurethane to a layer of vinyl resin by means of high frequency welding.
Most polymeric substances are difficult to adhere to because they usually contain a substantial amount of migrating substances such as low molecular weight materials, such as plasticizers, stabilizers, extenders, extrusion aids and the like which may bleed to their surfaces, making them very poor surfaces to bond to. Thus, if an extrudate is allowed to age for any appreciable length of time before a tape is applied to it, low molecular weight materials as described above may migrate to the surface of the extrudate making it a very difficult surface to adhere to. These low molecular weight materials may also migrate from the extrudate into the pressure-sensitive adhesive in contact with it on aging. Hence, even if a good initial bond is formed, the bond may degrade on aging because of these migrating substances. This may cause the pressure-sensitive adhesive to suffer severely in cohesive strength or may impair the adhesion between the adhesive and the extrudate or between the adhesive and the foam.
Moreover, a good bond between the pressure-sensitive adhesive on the foam tape and the plastic profile is difficult to achieve.
Migration is a well known problem with this type of product using pressure-sensitive adhesive and different manufacturers are taking various steps to try to reduce the effects of such migration. The usual means for reducing the rate of migration is by the use of a barrier film or coating, or by chemically treating the surface of the migratory component. Another method involves balancing the amount of low molecular weight material like plasticizers in the adhesive and in the extrudate so that the rate of migration of plasticizers from the adhesive to the extrudate is equal or nearly equal to the rate of plasticizer migration from the extrudate to the adhesive. All these methods are not completely satisfactory and it may be only a matter of time for the bond to fail.
The general object of the invention is to avoid and overcome the foregoing problems and form a laminate having a good bond between the layers thereof by a heat sealing or bonding action.
Another object of the invention is to provide a method of bonding a hot polymeric extrusion to a heat sensitive polymeric foam by a heat bonding layer and by low pressure.
Other objects of the invention will be made apparent as the specification proceeds.